title: A circular dichroism study of sheath contraction in pyocin R1.
abstract: Pyocin R1, a bacteriocin of Pseudomonas aeruginosa, is a protein particle shaped like a bacteriophage tail composed of a contractile sheath, core, baseplate and tail fibers. Alkaline treatment with sodium carbonate caused sheath contraction without considerable disassembly of other components. Circular dichroism (CD) spectra of pyocin R1 before and after the treatment, and of isolated sheath, were measured in wavelength regions around 220 and 290 nm at neutral pH. The alkaline treatment caused a red shift of the minimum from 208 nm to 212 nm. A marked difference in the CD spectrum was found in the near-ultraviolet region. THe difference is considered to be mainly due to a CD spectra change of tryptophan residues in the sheath subunits.
mesh_terms: D001430:Bacteriocins; D002254:Carbonates; D055598:Chemical Phenomena; D002621:Chemistry; D002942:Circular Dichroism; D008854:Microscopy, Electron; D011550:Pseudomonas aeruginosa / Q000032:analysis; D011709:Pyocins; D013056:Spectrophotometry, Ultraviolet
chemical_list: D001430:Bacteriocins; D002254:Carbonates; D011709:Pyocins; C005686:sodium carbonate